1. Field of the Invention
The present invention relates to a circuit for measuring and indicating the intensity of light adapted for use in an exposure meter.
2. Description of the Prior Art
For use in the exposure meter in a camera, there have been proposed several devices wherein the output electric signal of a light measuring circuit utilizing a photoelectric element is divided into plural levels and corresponding indicating elements such as light-emitting diodes are selectively lighted corresponding to said levels thereby indicating the adequacy of exposure, or in case of automatic exposure-controlled cameras, the lens aperture or shutter speed to be controlled.
In such devices, in order to indicate as much information as possible with a limited number of indicating elements, there is already known the following method. A light measuring and indicating circuit has n indicating elements and indicates (2n-1) levels or information by actuating m-th indicating element in accordance with m-th output level of the circuit, (m + 1)-th indicating element in accordance with (m + 1)-th output level, and both the m-th and (m + 1)-th indicating elements in accordance with the intermediate level between the m-th and (m + 1)-th levels.
Still in this method, however, there is required in the circuit for dividing the output signal of light-measuring circuit into plural levels (hereinafter called quatumizing circuit) a plurality of comparison switching circuits or flip-flops for every bit of a counter, of which the number corresponds to the number of said levels. For example a method disclosed in Japanese Laid-open patent application No. 91641/1974 requires at least (2n - 2) comparison switching circuits in order to indicate (2n - 1) levels with n indicating elements, while a method disclosed in U.S. Pat. No. 3,703,130 requires, in order to indicate 15 levels with 8 indicating elements for example, 4 flip-flops in combination with a binary counter or 15 flip-flops in combination with a shift counter using a shift register.